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. Author manuscript; available in PMC: 2019 Jul 25.
Published in final edited form as: J Am Chem Soc. 2018 Jul 11;140(29):9091–9094. doi: 10.1021/jacs.8b05724

Table 1.

Selected optimization experiments in the enantioselective intermolecular ruthenium catalyzed cycloaddition of benzocyclobutenones.a

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entry R1 R2 1a-1d R3 2a-2c 3a-3h yield (%), dr, rr er
1b H H 1a H 2a 3a 87, >20:1, >20:1 53:47
2b OMe H 1b H 2a 3b 83, >20:1, >20:1 81:19
3 OMe H 1b OMe 2b 3c 77, >20:1, >20:1 58:42
4 OMe H 1b OBn 2c 3d 79, >20:1, >20:1 76:24
5b OMe OTIPS 1c H 2a 3e 75, >20:1, >20:1 87:13
6 OMe OTIPS 1c OMe 2b 3f 78, >20:1, >20:1 89:11
7 OMe OTBS 1d OMe 2b 3g 74, >20:1, >20:1 80:20
8 OMe OTIPS 1c OBn 2c 3h 79, >20:1, >20:1 94:6
➡ 9c OMe OTIPS 1c OBn 2c 3h 96, >20:1, >20:1 97:3
a

Yields are of material isolated by silica gel chromatography. Enantioselectivity values were determined by HPLC analysis on a chiral stationary phase. (R)-SEGPHOS (Ar = phenyl).

b

Reaction was conducted from the diol oxidation level, 1a-1c (200 mol%).

c

1c (130 mol%), (R)-DM-SEGPEIOS (Ar = 3,5-xylyl). See the Supporting Information for further experimental details.